The present invention relates to a heating system, and more particularly to a heating system particularly adapted to greenhouses.
Traditional greenhouse structures, consisting of transparent panes of glass forming a roof to enclose a growing area, drawing air from the outside and having a heater for winter months, while adequate for many purposes, possess many shortcomings which make them unsuitable for year-round production of many types of fruits and vegetables in certain climatic conditions, e.g. in far Northern or far Southern climates where temperature and light conditions may be poor. For example, conventionally the heater is an oil or gas-fired heater, with piping for the oil or gas, and conduits for exhaust gases and heated air all being above the floor level of the greenhouse thereby creating potential shadows and blocking the passage of natural light to the plants. In addition, because such greenhouses often are not well sealed against the outside environment, unsuitable temperature differentials may be created within. As well, outside air which may contain substances which are not conducive to proper growth of plants, is permitted to enter. Also, by-products from the heater system, may be present in the environment within such greenhouses again causing reduced plant growth. There is an increasing awareness of the detrimental impact of impurities in the air on plant growth.
Patents of general background interest describing different types of greenhouse structures include Canadian Pat. No. 1,097,075 of Miller issued Mar. 10, 1981 (nutrient supply system for a controlled environment agricultural installation), Canadian Pat. No. 982,426 of Delano et al issued Jan. 27, 1976 (method of controlling amount of solar heat and light entering a greenhouse wherein the windows of the greenhouse are coated with a plastic film which is transparent under certain conditions and non-transparent under others), Canadian Pat. No. 955,748 of Glady et al issued Oct. 8, 1984 (reduction of the contact angle of water condensate droplets formed on the inner surface of greenhouse windows by coating that inner surface with a surface-active agent), U.S. Pat. No. 4,195,441 of Baldwin issued Apr. 1, 1980 (solar greenhouse in which plants are used as solar collectors to absorb solar radiation and store it in a heat reservoir beneath the greenhouse) and U.S. Pat. No. 4,352,256 of Kranz issued Oct. 5, 1982 (greenhouse structure including a central hub and arms comprising growth chambers extending radially outwardly therefrom).
Other patents of general background interest relating to heating systems for buildings include Canadian Pat. No. 848,301 of Bryant issued Aug. 4, 1970, Canadian Pat. No. 1,189,840 of Dirkes issued July 2, 1985 and U.S. Pat. No. 2,559,868 of Gay issued July 10, 1951.
It is an object of the present invention to provide a heating system which is particularly well-suited for greenhouses, which will provide clean air conditions within the greenhouse space, provide efficient transfer of heat as required to the greenhouse plants and which will not obstruct solar radiation passing to the plants within the greenhouse.